Interventions The trial interventions take place during vaginal birth after the delivery of the head. The head is supported in the spontaneous rotation that occurs after its delivery, and the shoulders are delivered according to randomization. The intervention is either primary delivery of the anterior or the posterior shoulder as illustrated in the additional movie files (see additional files 1 and 2). It is performed by the midwife placing her hands around the head of the baby and applying gentle traction in the appropriate direction.